Of the nine known members of the CCR4-NOT complex, CCR4/CAF1 are most important in mRNA deadenylation whereas the NOT1-5 proteins
are most critical for transcriptional repression. Whole genome microarray analysis using deletions in seven of the
CCR4-NOT genes was used to determine the overall mRNA expression patterns that are affected by members of the yeast CCR4-NOT complex.
Under glucose conditions,
ccr4 and
caf1 displayed a high degree of similarity in the manner that they affected gene expression. In contrast, the
not deletions were similar in the way they affected genes, but showed no correlation with that of
ccr4/caf1. A number of groups of functionally related proteins were specifically controlled by the CCR4/CAF1 or NOT modules. Importantly,
the NOT proteins preferentially affected SAGA-controlled gene expression. Also, both the CCR4/CAF1 and NOT group of proteins
shared much greater similarities in their effects on gene expression during the stress of glucose deprivation. BTT1, a member
of the nascent polypeptide association complex that binds the ribosome, was shown to be a tenth member of the CCR4-NOT complex,
interacting through CAF130. Microarray analysis indicated that BTT1 and CAF130 correlate very highly in their control of gene
expression and preferentially repress genes involved in ribosome biogenesis. These results indicate that distinct portions
of the CCR4-NOT complex control a number of different cellular processes.
Keywords CCR4-NOT - SAGA - BTT1 - Microarray
Communicated by S. Hohmann.
Yajun Cui, Deepti B. Ramnarain contributed equally to this manuscript.